The present invention, in some embodiments thereof, relates to a method and system for dehumidifying the interior of an enclosure and, more particularly, but not exclusively, to a method, apparatus and system for dehumidifying the interior of greenhouse enclosures in which plants are grown.
Greenhouses require that the air within it be controlled with respect to temperature and humidity in order to ensure that foliage temperature and transpiration rates are such as to maintain dry foliage and plant health. High humidity, especially free water on the plant foliage, promotes the development of foliar diseases, such as tomato blight, gray mould and downy mildews in various crops. These diseases inflict great harm on the crops, substantially reduce crop yield, and severely impair product quality. While pesticides are used to control these diseases, their use is limited for a number of reasons. Their use promotes pesticide resistance to many pathogens, and general governmental policy is to phase-out the use of some pesticides or to limit their use. Many consumers demand products having no pesticide residue. In addition, the use of such pesticides may unfavorably affect other environmental considerations.
Replacing the greenhouse air with external air is a customary method for decreasing the humidity in a greenhouse, and thereby the risk of producing free water on the foliage. External cold air, with low absolute humidity, replaces the warmer greenhouse air and absorbs the excess water that evaporates. Such a method, however, is very wasteful of energy.